Purpose:
To test whether retinal degeneration in a mouse model of monogenic maculopathy (Stargardt-like Dystrophy; STGD3) initially leads to the specific impairment of detailed vision (a stage at which movement detection remains spared) as occurs in its human counterpart.

Methods:
We relied on the TG1-2 ELOVL4 mouse model of STGD3; WT littermates served as controls. Visual acuity thresholds were determined in TG and WT mice (n=8 at 5 months of age, per group) by relying on two distinct behavioural tests: one based on movement detection (optokinetic reflex, OKR), the other based on detailed vision (cortically based forced decision, Y water maze).

Results:
Firstly, we confirmed previous findings that WT mice have higher visual acuity thresholds with the Y-water maze test (0.3457±0.0239) as opposed to the OKR test (0.3182±0.0104). Secondly, we found that TG mice had reduced visual acuity thresholds in the detailed vision test (0.2694±0.0149) when compared to WT mice (0.3457±0.0239). However, visual acuity thresholds of TG mice (0.3348±0.0078) were similar to those of WT mice (0.3182±0.0104), when assessed with the OKR test.

Conclusions:
While there is no anatomical way to directly assess whether retinal dystrophies such as STGD3 affect movement-based visual reflexes versus conscious detailed vision, our results imply that retinal degeneration in mouse models, such as in STGD3, can specifically impact on one aspect of vision. Furthermore, our results indicate that despite the fact that mice do not have a macula, they have distinct visual pathways established at the retina level, which can be differentially affected by specific mutations.